 | Home > Puma (Tdci) > Designing a digitally controlled heater system, help needed. |
 
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| B4Lamb Member Since: 21 Mar 2015 Location: Abergavenny, Wales Posts: 233   
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A few photos of the valve actuator.
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2nd Apr 2019 10:44pm |
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| B4Lamb Member Since: 21 Mar 2015 Location: Abergavenny, Wales Posts: 233
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 Click image to enlarge Click image to enlarge A few photos of the valve actuator. Click image to enlarge |
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2nd Apr 2019 10:55pm |
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| B4Lamb Member Since: 21 Mar 2015 Location: Abergavenny, Wales Posts: 233
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Things have moved on and I found I needed to fit an 'end of travel' microswitch to detect when the valve was fully shut. I had hoped that I could just over step the motor into stall condition and then use that as the fully closed reference position, however the rack and pinion upgrade provides so much force that there was a danger of stripping the gear teeth. A roller type switch was added creating a bit more complexity, all stuff that make Mata's Solenoid valve solution much more attractive and less complicated.
However, I now have a fully working control system and one I can start to fine tune. It seems to hold set point temperature well but i'll instrument it to get more precise and accurate results. At the moment I have two temperature sensors one in the Matrix output air flow and the other in the cabin but not fully located in a dash spare switch bezel yet. The first software iteration is just using proportional feedback control on the Matrix air. I'll add an outer loop to provide corrections to get the cabin air correct to the set point value as the next version. I'm using the original Bowden cable temperature control to adjust the user set point temperature. I eventually used a 40 mm long slider potentiometer with a 30 mm slide travel that works perfectly with the cable movement. The pot is located close to the heater valve in the engine bay where the Bowden cable ends up. I have fitted two tiny LEDs into a blank switch bezel on the dash to show when the heater valve is being opened or being closed. I found these handy so you can see at a glance what is going on. I'm not controlling fan speed yet but I have included facilities to add 3 FET drivera on three outputs to control speed at a later date. Next ill post some in car test results on a real trip although Winter is coming to an end so not an ideal test time now. "You are never to old to learn something new" |
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8th Apr 2019 7:36am |
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| B4Lamb Member Since: 21 Mar 2015 Location: Abergavenny, Wales Posts: 233
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Latest status of instrument cluster display mod to add an OLED for climate temperature info and other useful info. More info coming soon on the control system and sensors. "You are never to old to learn something new" |
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17th Apr 2021 11:18am |
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